1. Field of the Invention
The present invention relates to a fuel cell stack, and more particularly, to a fuel cell stack which can prevent a fuel cell stack module from being deformed at the time of a car accident.
2. Description of the Related Art
A Polymer Electrolyte Membrane Fuel Cell (PEMFC) or a Proton Exchange Membrane Fuel Cell refers to a device which produces electricity and water through an electrochemical reaction between hydrogen with oxygen. It has advantages of high power generation efficiency, high current density, high output power density, short starting time, and fast response to change in load, compared to other types of fuel cells.
A general fuel cell stack has a Membrane-Electrode Assembly (MEA) which includes a solid polymer electrolyte membrane which allows migration of hydrogen ions therethrough, and electrode layers (i.e. anode and cathode), disposed on both opposite principal surfaces of the solid polymer electrolyte membrane and coated with a catalyst which promotes a reaction between hydrogen and oxygen.
On the outer surface of each electrode layer, i.e. anode or cathode, a Gas Diffusion Layer (GDL) and a gasket layer are stacked in that order. The outer surfaces of the GDLs are provided with separators with flow fields which act as channels for reaction gases (i.e. hydrogen serving as fuel and air with oxygen serving as oxidant) and for coolant. End plates for supporting each component are combined with the outermost components to provide a compact structure.
FIG. 1 is a perspective view which schematically illustrates a fuel cell stack according to a conventional art. A fuel cell stack module 1 according to the conventional art typically includes 200 to 400 fuel cells. In order to obtain a fuel cell stack module 1 made up of a plurality of fuel cells, end plates 3 are placed on both opposite side surfaces of a stack of fuel cells, pressed up to a necessary pressure, and coupled to the stack of fuel cells using coupling bars 2. The stack of fuel cells disposed between the two end plates 3 are assembled into a single body by coupling respective ends of the coupling bars 2 to the end plates 3 using bolts.
The method of using the coupling bars 2 to assemble the fuel cell stack module 1 has an advantage that a sufficient surface pressure can be applied to the fuel cell stack module 1 and the volume of the fuel cell stack module 1 can be reduced. However, the fuel cell stack module 1 assembled using this method is vulnerable to bending and twisting in X and Z directions in an accident. FIGS. 2A to 2C show such bending and twisting motions in Z and X directions after an accident.
In FIGS. 2A-2C, the fuel cell stack module 1 which is assembled using the coupling bars 2 is deformed and is likely to malfunction when receiving an impact. This can result in a short-circuit within the fuel cell stack module 1, resulting in fire. As such, there is a need for a structure which can prevent damage to the fuel cell in the event of an impact.
The foregoing is intended merely to aid in the understanding of the background of the present invention, and is not intended to mean that the present invention falls within the purview of the related art that is already known to those skilled in the art.